Lecture (6 ) Electric Flux Density , Gauss’s law and Applications

Electric Flux Density ( ? )
From the concept of electric field flux – to the calculation of electric fields of complex charge distributions.

Applies to any vector field a ?=( r ?), the flux of the field a ?=( r ?) through a small element of surface dA ? is



For calculate the flux of uniform electric field through the surface shown in the figure.

By use the equation :


Therefor the value of flux is

Flux through closed surfaces , the net flux of the electric field is:

The integral is taken over the whole surface

Also any point charge at the center of a spherical surface the (E ) ? ? dA ? ( Cos ? = 1 ) see the down figure

In this case the value of flux is

The flux for point charge place outside the surface is equal to zero

The flux magnitudes for two surface same as in the down figure is taken same value.

2.5 Gauss’s law – Maxwell’s Equation




2.6 Applications of Gauss’s law









For two parallel plates ( Conducting plates )
E= ?2??_1/?_O E = 0 E ? E = 0
?_1= ?/?2??_O
E= ?/?_O
2?1